From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Experiments conducted on ignition coils, comparing their performance and resistance.
| Identifier | ExFiles\Box 45\4\ Scan110 | |
| Date | 29th November 1922 | |
| EFC. PB.65. Nov.29th 1922. EXPERIMENTS IN CONNECTION WITH COILS Experiments in connection with coils, have recently been carried out on the car and on the bench. Those carried out on the car were :- (1) Temperature attained by coil on engine obtained by rise in resistance of secondary winding. (2) Test of the insulation of the whole of the H.T. circuit at once. Those experiments carried out on the bench were:- (3) Effect of temperature on low speed sparking of coil. (4) Effect of deletion of hedgehogging ends of coil. Details of the experiments are as follows :- (1) In this experiment two coils were used G.II. 12, and SB.{Mr Bull/Mr Bannister}9. The resistance of the secondary of G.II 12 cold, was first obtained, and then again found after it had been allowed to heat up in position on the engine; the engine in the meantime being fired by SB.{Mr Bull/Mr Bannister}9 coil. The coils were then changed over and the observations repeated with coil SB.{Mr Bull/Mr Bannister}9, with the difference, however, that the resistance cold was not taken until the following morning in order to let the coil get properly cold. The fact also must be taken into account of this coil having fired the engine previous to its resistance hot being found, and thus may have been warmed up internally as well. The results are as follows :- Coil G.II.12. Coil SB.{Mr Bull/Mr Bannister}9 R at 10.5oC = 6,987 ohms. R at 17oC = 8,260 ohms. R " 0oC = 6,690 " R " 0oC = 7,710 " R " T oC = 8,040 " R " T oC = 9,610 " Temp. corresponding to Temp. corresponding to 8,040 ohms = 48.1oC. 9,610 ohms = 58.7 oC. Contd. | ||